Full-Duplex Wireless-Powered IoT Networks With
Unmanned Aerial Vehicle
(Invited Paper)
Han-Ting Ye
†
, Xin Kang
†
, Member, IEEE, Ying-Chang Liang
†
, Fellow, IEEE, Jingon Joung
‡
, Senior Member, IEEE
†
University of Electronic Science and Technology of China (UESTC), Chengdu, P. R. China.
‡
Chung-Ang University, Seoul, South Korea.
E-mails: yhtxyfs@gmail.com, kangxin@uestc.edu.cn, Liangyc@ i eee.org , jgjoung@cau.ac.kr
Abstract—This paper investigates unmanned aerial vehi-
cle (UAV)-aided full-duplex wireless powered Internet-of-things
(IoT) networks, where a UAV equipped with a full-duplex hybrid
access point (HAP) serves multiple sparsely distributed energy
constrained IoT sensors. The UAV hovers above each sensor for
one time slot for information collection. It is assumed that the
transmission range of the UAV is limited, and thus, the energy
broadcasted from the UAV is only available for the next adjacent
sensor to harvest in the case where the sensors are sparsely
distributed in the IoT networks. Since the full-duplex mode is
adopted and no initial energy harvest time is allocated to the
entire IoT networks, the coupling time relationship makes the
solution of the model more challenging. Under the proposed
model, we formulate two problems: sum-throughput maximiza-
tion (STM) and total-hover-time minimization (THTM). For the
STM problem, the optimal solution is obtained by applying
convex optimization techniques. For the THTM problem, by
exploiting the properties of the coupled constraints, we propose
an algorithm to obtain an optimal solution. Finally, the numerical
results show that the performance achieved by the proposed
optimal time allocation scheme outperforms an equal time
allocation scheme, under block-fading and line of sight (LoS)
channels.
I. INTRODUCTION
Internet-of-things (IoT) is one of the current hot tech-
nologies with a wide range of applications [1], [2], such
as smart cities, smart agriculture. However, since sensors
may be located at the remote locations, it requires up to 10
years of battery life. Although we can prolong the battery
life by replacing or recharging the batteries periodically, it
may be inconvenient (for a sensor network with thousands
of distributed sensor nodes) and dangerous (for the devices
located in extremely harsh environments). Energy harvest
(EH) has become a promising approach to solve the energy
problem of IoT networks[3]. In such situations, the low-power
IoT networks need to build a hybrid access point (HAP) [4]
to provide a stable energy supply and regular data collection
(DC) for the ground sensors. However, in practice, sensors
are usually located at remote area or extreme environment, it
is difficult to supply energy to sensors from a fixed HAP. A
viable option is to set up more HAPs in the target area to
provide energy supply and DC. However, due to the sparse
distribution of sensors, the cost will be very high.
Recently, unmanned aerial vehicle (UAV) has drawn signif-
icant interest in many applications. Particularly, by mounting
communication transceivers to low-altitude UAVs, UAVs can
be used as aerial mobile base stations or relays to help enhance
the performance of terrestrial wireless communication systems
[5]. Compared to conventional networks where APs are fixed
at given locations, wireless communication networks employ-
ing a UAV-mounted access point (AP) exhibit cost-efficiency
and deployment flexibility.
In previous works, UAV has been applied to wireless pow-
ered communication networks (WPCNs). By using its fully
controllable maneuverability, UAV can adjust the positions
over time to flexibly adjust the distance and communication
time with the ground sensors, hence improving the efficiency
for both EH and DC. In [6], a wireless sensor network
charging by a UAV under a fixed line trajectory was studied.
The works in [7] and [8] considered the UAV-enabled EH
systems, but they did not take into account the collection of
sensor information.
In this paper, we study a new UAV-aided full-duplex wire-
less powered IoT networks, where K single-antenna sensors
are supported by a two-antenna UAV. A close work has
been completed in [9], [10], [11]. However, in [9] they just
considered a fixed HAP for all users to perform EH and DC in
full duplex mode. Specifically, due to the sparse distribution
of sensors in the IoT networks, UAV can only charge one
sensor when UAV hovers over each sensor for DC in this
paper rather than all sensors via HAP in [9]. It is because the
EH time of all users includes the initial moment, problem-
solving difficulty is greatly reduced in [9]. Different from
[10] and [11], the UAV is limited to have one single antenna.
Therefore, UAV cannot use full-duplex mode to perform EH
and DC on sensors in IoT networks. The time at which all
the sensors in the model perform EH is also allocated at the
initial moment so that the problem is easy to solve. At the
same time, in some harsh extreme environments, IoT networks
sensors are far apart, their solutions also can not be achieved.
In this paper, the EH time of each sensor is the DC time of
the last sensor, hence the coupling time relationship makes
the solution of the model more challenging. From a practical
point of view, we are interested in the following two problems:
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